This invention relates to injection molding and more particularly to an improved stack molding system for conveying melt from a fixed platen to a movable platen.
Hot runner injection molding systems utilizing stack molding to convey melt to a manifold in a movable platen to increase the number of cavities are well known in the art. An early example using valve gated nozzle is shown in the applicant's U.S. Pat. No. 4,212,626 which issued July 15, 1980. In order to avoid the difficulties and problems associated with valve gating, the applicant's more recent U.S. Pat. No. 4,586,887 which issued May 6, 1986 provides a stack molding system which uses heated probes to provide a hot tip. While this works satisfactory for some materials, polymer insulated hot runners are difficult with easily stringing materials such as polypropylene, polyethylene, nylon, etc.